If you would go with non "smart" locks, then there are lots of basic keypad locks available. The ones we have here were from Lowes "Gatehouse" brand, and they have a physical key as well as 6-digit codes. Once can set several of those 6-digit codes to give away, including one-time codes etc.

The only trick would be to ensure that a "guest" doesn't add their own code to the lock.. But I think they would need to know the "master" code to be able to do that.

Cheers